DASH in Twitch: Adaptive Bitrate Streaming in Live Game Streaming Platforms

DASH in Twitch:Adaptive BitrateStreaming in Live GameStreaming PlatformsKarine Pires, Gwendal SimonTelecom Bretagne, FranceNov 2014

Live Streaming : A New ContextCloud Delivery Process

2 / 19 K. Pires, G. Simon DASH in Twitch


more and morenon-professionalbroadcasters



CDNmore and moreheterogeneousend-viewers



CDN

Data-Center



CDN

Data-Center

Adaptive Streaming1 video stream = k representations



CDN

Data-Center

+55 millions unique visitors

4th in US internet traffic


Two options for the delivery process

Traditional Process

RawVideo

IngestServers

DeliveryServers


Two options for the delivery process

Traditional Process

RawVideo

IngestServers

DeliveryServers

Transcoding Process

RawVideo

IngestServers

TranscodeServers

DeliveryServers


Which live streams to transcode

TraditionalProcess↓ CPU

↓ QoE

↑ BW

TranscodingProcess↑ CPU

↑ QoE

↓ BW

Trade-off

Live stream ?


Our contributions

Adaptive Bit-Rate streaming in Twitch :Real traces from TwitchDecision of which channels should be delivered with ABRComparison of different decision strategies


A Tour on Twitch


What is a broadcaster

A broadcaster streaming two gaming sessions

online online

nb. of viewers

timet1 t ′

1 t2 t ′2

session 1 session 2


Data retrieval

For 3 months → from 6 Jan. to 6 Apr.

time

allchannelsof one

snapshot

9 :00 9 :05 9 :10 9 :15 9 :20every five minutes → one snapshot

Dataset available : http ://dash.ipv6.enstb.fr/dataset/twitch/8 / 19 K. Pires, G. Simon DASH in Twitch

How many online broadcasters

0 10 20 30 40 50 60 70 80 900

2K

4K

6K

8K

10K

Days

Nb.

ofon

line

chan

nels

min max


How much bandwidth is needed

0 10 20 30 40 50 60 70 80 900

1

2

Days

Ban

dwid

th(T

bps)

min max


Raw videos properties

240p 360p 480p 720p 1080p0

0.2

0.4

0.6

Representation

Sess

ions

ratio



240p 360p 480p 720p 1080p0

0.2

0.4

0.6

Representation

Sess

ions

ratio

0.1 1 2 100

0.2

0.4

0.6

0.8

1

Video bit-rate (Mbps)CD

Fof

the

sess

ions

480p



240p 360p 480p 720p 1080p0

0.2

0.4

0.6

Representation

Sess

ions

ratio

0.1 1 2 100

0.2

0.4

0.6

0.8

1

Video bit-rate (Mbps)CD

Fof

the

sess

ions

480p 720p 1080p


Selecting the ABRstreams


When to decide a stream should be transcoded

At-startupStrategy

transcoding decision

timet1 t ′

1

On-the-flyStrategy

timet1 t ′

1

transcoding decision

transcoding traditional


Strategies

None : no ABRAll : all streams are streamed with ABR

Top-50 (at-startup) : streams that were popularThreshold-1000 (on-the-fly) immediate popularity


Strategies

None : no ABRAll : all streams are streamed with ABRTop-50 (at-startup) : streams that were popular

Threshold-1000 (on-the-fly) immediate popularity


Strategies

None : no ABRAll : all streams are streamed with ABRTop-50 (at-startup) : streams that were popularThreshold-1000 (on-the-fly) immediate popularity


Evaluation settings

Sessions → Twitch datasetViewers → DASH datasetABR → proportional to raw video


Results : degraded viewers served

0 10 20

0

0.5

1

None

All

Days

Vie

wer

sra

tioTop Threshold


Results : costs evaluation

None All ThresholdTop0

50

100

150

-40%-39%

+5%

Strategies

Tota

lPric

e($

M)Delivery Transcode


Conclusion


Discussions

preliminary work=global picture→details neglectedmore formal and accurate formulationmore precise QoE estimationbetter transcoding needs modelmanagement of different hardware resources

more efficient strategies can be designedsophisticated strategiesstatistical approaches for popularity forecasting


Discussions

preliminary work=global picture→details neglectedmore formal and accurate formulationmore precise QoE estimationbetter transcoding needs modelmanagement of different hardware resources

more efficient strategies can be designedsophisticated strategiesstatistical approaches for popularity forecasting


DASH in Twitch: Adaptive Bitrate Streaming in Live Game Streaming Platforms

Engineering